Device for supporting a machine part when subjected to force

ABSTRACT

The invention relates to a device for supporting a first machine part during the subjection to force of a second machine part that is mounted on or accommodated in said first machine part, especially a device for supporting a shaft (1) with a tie rod (2) while said tie rod (2) is being subjected to force, e.g., for changing parts of tools that are mounted on the shaft in automatic processing machines. A first adjustable structural element is provided for introducing a counter force into the first machine part, for supporting said first machine part in a stable position, and a second adjustable structural element is provided for subjecting the second machine part to a force.

FIELD OF THE INVENTION

The invention relates to a device for supporting a first machine partwhen a second machine part is subjected to force. The second machinepart is mounted on the first machine part. The device supports a shafthaving a tension rod, which can be displaced in the axial direction,when the tension rod is subjected to force.

BACKGROUND OF THE INVENTION

In the case of rotating systems, it is generally required for a force tobe introduced when at a standstill, and any contact between the rotatingpart and the force-introducing unit has to be avoided during therotation. This is the case with part-changing mechanisms on rotatingparts, for example in the case of spindles in automatic processingmachines. In this case, the housing and the piston rod of the unit forintroducing the force are conventionally arranged in a manner such thatthey can be displaced freely, and there is a fixed collar on therotating machine part, against which the parts, which are provided witha gripping means, for example in the form of ratchet levers, and areconnected to the cylinder housing, come to bear first and thus enclosethe force flux within themselves before the force-introducing actuatingforce becomes effective. Solutions of this type frequently requireconsiderable structural space.

Another solution, but one which is fairly unfavourable, is to supportthe forces which act outwards in the mounting of the rotating machinepart without an internal frictional connection, which has a negativeeffect on the accuracy, the wear and the running properties.

OBJECTS AND SUMMARY OF THE INVENTION

The invention is based on the object of providing a particularly compactdevice for supporting a first machine when a second machine part issubjected to force.

DETAILED DESCRIPTION OF THE INVENTION

The device according to the invention comprises a first component whichcan be adjusted hydraulically, pneumatically or in an electricallypowered/electromagnetic manner via a threaded drive, for introducing acounterforce into the first machine part for the purpose of supportingthe first machine part in a stable position, and a second componentwhich can be adjusted powered/electromagnetic manner via a threadeddrive, for subjecting the second machine part to force. The first andsecond components are activated at the same time and, in the manner oftwo cylinders acting counter to each other, equalize the internal forceflux, in a manner similar to how this happens when a syringe isactuated.

In this case, the first and second components can have a pistonarrangement, a diaphragm cylinder or an electromagnetic/electricallypowered adjusting mechanism.

In the case of a design as a piston arrangement, the relief piston ofthe first component for introducing a counterforce is placed against acollar connected fixedly to the first machine part. At the same time,the relief piston comes to bear against the cylinder housing on asurface which is coordinated precisely in terms of size with the collar,which supports the counterforce of the relief piston, with the resultthat force is not introduced into the first machine part during supportof the latter when the second machine part is subjected to force.

At the same time, in the second component a release piston, which isintended to move the second machine part in or on the first machinepart, is subjected to pressure. The release piston first of all comes tobear against the second machine part and then displaces the secondmachine part relative to the positionally fixed first machine part. Theforce which is introduced via the release piston is held by the reliefpiston, which bears against the collar of the first machine part, withthe result that the force flux is enclosed within it.

The first and second components advantageously have diaphragm cylinders,which results in a particularly short constructional length which caneasily be sealed. The diaphragm cylinders can be automatically resilientor can be brought into the starting position by an additional springarrangement.

An adjusting mechanism which can be activated in a particularly simplemanner is achieved with an electromagnetic or electrically poweredadjustment. This saves on structural space for hydraulic or pneumaticsupply ducts, with the result that an electromagnetic/electricallypowered adjustment can be used, for example, in the case of multi-stageadjusting systems.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description the invention will be described in moredetail with reference to the appended drawings. In the drawings

FIG. 1 shows a cross section of the device having diaphragm cylinders,

FIG. 2 shows a cross section of the device having a piston arrangement,

FIG. 3a shows a first embodiment of a diaphragm part according to FIG.1,

FIG. 3b shows a second embodiment of a diaphragm part according to FIG.1,

FIG. 4 shows an illustration of a diaphragm cylinder according to FIG. 1having a diaphragm part according FIG. 3b,

FIG. 5 shows a cross section of the device havingelectromagnetic/electrically powered adjustment, and

FIG. 6 shows a schematic illustration of an embodiment havingelectromagnetic/electrically powered adjustment.

In FIG. 1, the device according to the invention is illustrated in anembodiment having diaphragm cylinders. Mounted in a rotatably mountedshaft 1 (first machine part) is a tension rod 2 (second machine part)which can be displaced in the axial direction, is held under tension bymeans of a spring assembly 3 and in the process holds or securely clampsa part, for example a replaceable tool (not depicted), which is mountedon the other end of the shaft.

In order to replace this tool, the tension rod 2 has to be displacedcounter to the spring force of the spring assembly 3 in the direction35. For this purpose, the rotational movement of the shaft 1 is broughtto a standstill. The pressure chamber 5 of the release piston 4 (secondcomponent for introducing force) is subjected to a pressure medium andmoves the non-rotating release piston 4 counter to the tension rod 2 inthe direction 35 by the distance a, which is necessary so as to prevent,when the shaft 1 is rotated, any contact between the rotating shaft 1(or tension rod 2) and piston 4. After the stroke a, the force ofpressure builds up at the release piston 4 to the extent necessary inorder to displace the tension rod 2 counter to the spring assembly 3 toa sufficient extent axially in the direction 35 that the tool (notdepicted) at the other end of the shaft 1 is released. Since the springassembly 3 is supported in the shaft 1, this release force which isintroduced also acts on the shaft 1, and therefore on the mounting withwhich the shaft 1 is mounted in the machine body. In order to avoid thisaxial additional load on the mounting, the shaft 1 is supported.

According to the invention, a collar 6 is provided for this purpose,which collar is connected fixedly to the shaft 1 and against whose planebearing surface 7 the relief piston 8 (first component) bears, andtherefore prevents any axial displacement of the shaft 1. The reliefpiston 8 is placed at the same time against the bearing surface 7 andagainst a stop surface 9 on the housing part 10. The free stroke b ofthe relief piston 8 to the bearing surface 7 and stop surface 9 isexactly the same, with the result that the shaft 1 is held in itsposition by the relief piston 8 via the collar 6 in a play-free andforce-free manner.

The pressure which has built up in the pressure chamber 11 produces aforce on the relief piston 8, which is greater than the release force ofthe release piston 4 and is supported on the stop surface 9. In thiscase, as illustrated in FIG. 1, the release force can be produced in aninherently closed (hydraulic) system or can act on the tension rod 2from the outside.

The relief piston 8 is part of a subassembly which comprises the housing12 together with the pressure chamber 11 and the orifices 13 for theinflow of the pressure medium of the diaphragm 14. The diaphragm 14 isconnected to the housing 12 via the clamping ring 15 and in a leakproofmanner to the annular relief piston 8 along a narrow annular surface 16.The relief piston 8 seals off the pressure chamber 11 with respect tothe housing 12 by the sealing ring 17. When subjected to pressure, therelief piston 8 completes the short stroke movement b and is pulled backinto its neutral position illustrated by the resilient diaphragm whenthe pressure is shut off. The diaphragm 14 is an annular disc made ofthin, resilient material, preferably spring band steel, and interactswith the relief piston 8 as a piston which is of sufficiently largedimensions in order to apply the required axial counterforce, and pullsthe relief piston 8 into the neutral position when unpressurized.

The release piston 4 faces the relief piston 8 and is connected via thehousing part 10. The release force of the release piston 4 is producedin the pressure chamber 5. The pressure medium, which is suppliedthrough the orifices 18, presses against the diaphragm 19, which istightly clamped on its outer diameter between the housing part 10 andthe housing part 20 of the release unit and is connected on its innerdiameter to the release piston 4, and moves the release piston 4 in thedirection 35 towards the tension rod 2.

After the idle stroke distance a, which is the safety distance which isnecessary in order to prevent any contact between the tension rod 2 andrelease piston 4 while the shaft 1 is rotating, the release piston 4presses against the tension rod 2 and displaces the latter relative tothe shaft 1, after overcoming the spring force of the spring assembly 3,in order to enable the tool to be released and replaced. In the process,the shaft 1 is supported by the relief piston 8, which bears against theshaft collar 6, with the result that the shaft remains force-free. Theforce flux is inherently enclosed by the release piston 4 via the shaftcollar 6, the relief piston 8 and the connected housing parts 12, 10 and20.

Since the stroke of the release piston 4 is significantly larger thanthat of the relief piston 8, a two-part diaphragm can be provided. Thetear-resistant, but very flexible, diaphragm 19 comprises a reinforced,rubber-coated fabric and is supported against bulging by the diaphragmpart 21. This diaphragm part 21 preferably consists of a metal plate orvery firm plastic, and is slit in a suitable manner starting from theinner edge radially as far as the clamping diameter in order to increasethe axial mobility (cf. FIG. 3a).

The resetting movement of the diaphragms is achieved by means of springs22 which press against the collar 23 on the release piston 4. Therelease unit is sealed off between the housing 20 and release piston 4by the sealing ring 24. The diaphragm surface of the release unit(second component) is, in order to obtain good axial mobility,significantly larger than the diaphragm surface of the relief unit(first component) for introducing the counterforce. Accordingly, thepressure chambers 11 and 5 are supplied with different pressures throughthe orifices 13 and 18.

Since, when being subjected to pressure, the volumetric flow in therelief unit is substantially smaller than in the release unit, it isensured that, when simultaneously subjected to pressure (by means of acommon hydraulic system), the relief piston 8 bears against the collar 6before the release force by means of the release piston 4 becomeseffective. In order to monitor the release movement of the tension rod2, a signal ring 25 is connected to the tension rod 2, said signal ringparticipating in the stroke movement, so that the sensor in the orifice26, which sensor is fastened fixedly or adjustably in the housing part10, is activated. One or more sensors can be mounted next to one anotheror offset around the circumference (not depicted).

In FIG. 2 the first component has a piston arrangement. The shaft 1 isconnected fixedly to the collar 6. The bearing surface 7 of said collaris at precisely the same distance b from the relief piston 8 as thelatter is from the stop surface 9 on the housing cover 34. The reliefpiston 8 is subjected to pressure medium through the orifices 13 in thepressure chamber 11 and is moved against the bearing surface 7 and stopsurface 9, where it bears with a force which is greater than the force Fof the release piston 4 (not depicted), which force is introduced at thetension-rod head 36 of the tension rod 2. The relief piston 8 is setback into the starting position by means of the spring force of thespring 37 or, if the relief piston 8 is correspondingly designed as adouble-acting piston, by means of the counterpressure (not depicted).

FIG. 3a shows one possible embodiment of a diaphragm part 21 whichsupports the flexible diaphragm 19 over its entire surface. Thediaphragm part 21 is at the same time concentrically clamped by itsouter edge zone together with the diaphragm 19 between the housing parts10 and 20. The supporting surface of the diaphragm part 21 for theflexible diaphragm 19 is separated into a multiplicity of sectors 28 bythin, radial slots 27. The mobility of the individual sectors 28 is madeeasier, in a hinge-like manner, by the tangential slots 29, which leaveonly a sufficiently short connection 30 behind. Since the inner edge ofthe diaphragm part 21 is free, a supporting element, which overall isreadily moveable, is therefore produced, said supporting element beingmoved to and fro by the compressive force of the diaphragm 19, on theone hand, and by the restoring force of the spring 22, on the otherhand.

FIG. 3b shows a further design of a diaphragm part 21. Here, thesupporting surface of the diaphragm part 21 for the flexible diaphragm19 comprises individual segments 31 which are not connected to oneanother and are fitted at the outer edge, by means of a cylindricalthickening 32 in the housing part 10, into an annular groove 33 in amanner such that they can tilt in the axial direction (cf. FIG. 4).These segments 31 bear against the flexible diaphragm 19 and are pressedagainst the diaphragm 19 by means of the spring 22 and the collar 23 onthe release piston 4. In FIG. 4, the two segments 31 and 31 a of thediaphragm part 21 are also illustrated in a relaxed and actuated(depiction using dashed lines) switching position of the release piston4.

FIG. 5 shows a further embodiment of the device havingelectromagnetic/electrically powered adjustment, in order to prevent anaxial movement in the force direction F. The axially moveable stop 38 ismoved by an electric motor or rotary magnet consisting of the stator 39and the rotor 40. The stator 39 is enclosed by a thick-walled sleeve 41which is pressed into the housing 42, which in turn is held in atwist-proof manner by the spindle sleeve 43. The rotor 40 is fastened ina twist-proof manner on the axial part of the stop 38. The stop 38 isconnected rotatably to the housing 42 via the thread 44, as a result ofwhich, when the stop 38 is rotated by the electric motor/rotary magnet,the axial movement a′ of the stop 38 between the stop surface 45 and thestop surface 46 of the housing part 10 takes place.

When the stop 38 is activated, the stop surface 46 and the collar 6 ofthe shaft 1 are made contact with via its stop surface 45, and thecollar 6 is supported. The deactivated stop 38 bears against the sleevestop surface 47 of the sleeve 41. The thread 44 is self-locking, withthe result that the stop surface 45 cannot be displaced relative to thestop surface 46 under the load F. The electric motor/rotary magnet issupplied with power via wires (not depicted).

FIG. 6, along with FIG. 5 shows a further schematic illustration of anelectromagnetic/electrically powered adjustment. A thread 61 is mountedin the air gap between the stator 39 and and rotor 40. The stop 38 isshown. The stator 39 has an inner part (for example made of plastic)having an inner thread 48 which is screwed to an outer part of the rotor40 with an outer thread 49. By this means, the rotor 40 is mountedradially and when rotated in the stator 39 executes the adjustingmovement a′ according to FIG. 5.

The electromagnetic/electrically powered adjusting mechanisms depictedin FIGS. 5 and 6 can be combined with all of the arrangements depictedor described in FIGS. 1-4 for activating the release piston 4.

What is claimed is:
 1. Device for supporting a first machine part when asecond machine part is subjected to a force in a longitudinal axialdirection thereof, wherein said second machine part is mounted on thefirst machine part, wherein the first machine part is a shaft (1) havingthe second machine part which is a tension rod (2), which tension rod isdisplaced in the axial direction when the tension rod (2) is subjectedto the force, comprising: a first adjustable component provided forintroducing a counterforce, to counter the force from the second machinepart, into the first machine part for the purpose of supporting thefirst machine part in a stable position relative to the second machinepart, the first adjustable component has an electromagnetic orelectrically powered adjusting mechanism, and a rotor (40), wherein therotor (40) is connected to an adjustable stop (38) and the stop (38) isconnected displaceably to a housing (42) via a thread (44); and a secondadjustable component provided for subjecting the second machine part tothe force, wherein the second adjustable component is designed as adiaphragm connected to a moveable piston.
 2. Device according to claim1, wherein the shaft (1) has a collar (6) for use as a bearing surfacewhen introducing the counterforce.
 3. Device according to claim 1,wherein the tension rod (2) has a tension rod head (36) for use whenbeing subjected to force.
 4. Device according to claim 1, wherein thesecond component has a release piston (4) for subjecting the secondmachine part or the tension rod (2) to force.
 5. Device according toclaim 4, wherein the release piston (4) is arranged resiliently via aspring element (22).
 6. Device for supporting a first machine part whena second machine part is subjected to a force in a longitudinal axialdirection thereof, wherein said second machine part is mounted on thefirst machine part, wherein the first machine part is a shaft (1) havingthe second machine part which is a tension rod (2), which tension rod isdisplaced in the axial direction when the tension rod (2) is subjectedto the force, comprising: a first adjustable component provided forintroducing a counterforce, to counter the force from the second machinepart, into the first machine part for the purpose of supporting thefirst machine part in a stable position relative to the second machinepart, wherein the first component has an electromagnetic or electricallypowered adjusting mechanism, a stator (39) and a rotor (40), and therotor (40) is connected to an adjustable stop (38) and the stop (38) isconnected displaceably to a housing (42) via a thread (44); and a secondadjustable component provided for subjecting the second machine part tothe force, wherein the second adjustable component is designed as adiaphragm connected to a moveable piston.